What starts as a simple runny nose can lead to a much more severe disease that could prove fatal to your horse. It’s wise to make sure that you have horse medical insurance if your horse does become ill. Here are five of the deadliest diseases to watch out for:

1. Potomac Horse Fever (PHF)

If you pasture your horse near a creek or water, you should watch out for symptoms of this disease. It’s caused by bacteria found in flatworms that live in snails. The ailment is more prevalent in warmer months when the flatworms leave the snails and go into the water. Horses can ingest the flatworms through drinking water or contract them from eating grass. Symptoms of PHF include loss of appetite, fever, diarrhea and mild colic. Even a mild case of PHF can turn deadly if it’s not treated right away.

2. Equine Herpesvirus (EHV)

Equine Herpesvirus is an extremely contagious virus that spreads to other horses through nasal discharge, water troughs or contaminated feed. It typically affects young horses. If your horse looks like it’s trying to maintain its balance by leaning against a fence or wall, this could be a sign of EHV. Other symptoms include lethargy, nasal discharge, dribbling urine and weakness in the hind legs. Horses expected of having EHV should be isolated immediately.

3. Equine Influenza

The most common infectious disease in horses is equine influenza or the flu. This highly contagious virus attacks a horse’s respiratory tract. Your horse can get influenza through contact with an infected horse or being in the same area as an infected horse. Symptoms include fever, nasal discharge, lethargy, loss of appetite and a dry cough that lasts for weeks.

4. Strangles

Streptococcus equi, or Strangles, is another contagious disease affecting horses. The infection results in abscesses on lymphoid tissue of the horse’s upper respiratory tract. Signs of strangles include nasal discharge, fever, swollen lymph nodes and difficulty swallowing. If the abscesses spread to other parts of the horse’s body, the condition is most often fatal.

5. Tetanus

Horses can contract tetanus from a wound that becomes contaminated from soil or manure containing Clostridium tetani bacteria. The bacteria can multiply rapidly and produce toxins in the horse that result in difficulty moving or eating, sweating, stiffness, and spasms. About 50 – 75 percent of tetanus cases result in death.

Most of these diseases can be prevented through vaccinations, so make sure to talk to your veterinarian about proactive measures.